The fixed/free format detector counted a line as fixed-format only when its
first six columns were blank (`^ {6}[ *\-/ ]`). Legacy mainframe COBOL — the
main reason to have a COBOL extractor — puts a sequence NUMBER in columns 1-6,
so every such file scored zero fixed markers and was classified free-format.
In free mode the code is taken verbatim (no column-8 slice), so the sequence
number stays glued to the statement: `000400 MAIN-PARA.` no longer matches the
paragraph anchor `^NAME .? .$`, and the whole procedure layer disappears. A
seven-line program with two paragraphs and a PERFORM collapsed to just the file
and program nodes — zero paragraphs, zero `calls` edges — silently.
Match a sequence area that is six spaces OR six digits, followed by a valid
indicator column (space = code, `*`/`/` = comment, `-` = continuation, `D` =
debug). Once the file is correctly read as fixed-format the existing
column-8..72 slice strips the sequence number and paragraphs/PERFORMs resolve
as they should. Blank-sequence fixed-format and genuinely free-format source are
unaffected (a 6-digit prefix is not something free-format code begins a line
with).
Regression test: a sequence-numbered program now yields its program, both
paragraphs, and the PERFORM `calls` edge — and fails on the old detector.
Co-Authored-By: Claude Opus 4.8 <noreply@anthropic.com>
Claude-Session: https://claude.ai/code/session_01JJbLfztSxm2tH5cJwBbe9q
